This invention relates to the preparation of a novel emulsifier; emulsions prepared with the emulsifier; and products prepared utilizing the emulsifier. Half-ester starch derivatives may be created by reacting starch and a substituted dicarboxylic acid anhydride so as to form alkenyl succinic anhydride starch derivatives. Native starch granules are insoluble in cold water. When native starch granules are dispersed in water and heated, however, they become hydrated and swell. With continued heating, shear, or conditions of extreme pH, the granules fragment and the starch molecules are dispersed in the water, i.e., solubilized, resulting in a nongranular, dispersed starch.